Computer Aided Design Advances Breast Reconstruction

Computer aided design (CAD) can be used to produce accurate molds of a patient's healthy breast prior to tissue reconstruction procedures, according to a new study.

Researchers at the Queensland University of Technology (QUT; Brisbane, Australia), Singapore Polytechnic (Singapore), and other institutions employed laser scanning to creating an accurate digital representation of the breasts and surrounding tissues. The obtained model was used to fabricate a customized mold that was then employed by the surgeon as an intraoperative template throughout the entire free-flap autologous tissue reconstruction of the breast removed due to cancer. The technique has so far been successfully used in three breast tissue-reconstruction operations.

A solid breast model was also derived from the imaged data and digitally processed for the fabrication of customized biodegradable three-dimensional (3D) scaffolds on which the patient's own tissue could be grown, using a novel generic algorithm for creating the required porosity within the solid model. Since the scaffold is biodegradable, it will disappear after two to three years. On the other hand, silicone implants (the most common material used in breast reconstruction surgery) remains forever and can cause long-term problems, such as fibrous encapsulation. The study was published in the September 2011 issue of Biofabrication.

“When you think about the volume of a breast, to recreate this with randomly shaped tissue removed from elsewhere on a patient's body is quite difficult. Normally patients have two or three operations to enable the surgeon to correct and get the shape right,” said lead author Prof. Dietmar Hutmacher, PhD, of the QUT. “With scaffolding you can get the shape and form right from the beginning, using a small amount of tissue - around one cubic centimeter - from the patient.”

To form the 3D scaffolds, the researchers used tetrahedral volumetric meshes to create intermediates, using established methods and a common finite element (FE) modeling analysis-software package. For the second step, an algorithm was designed and employed to create struts of a given thickness around each edge length of all tetrahedrons, joining at their intersections to create a watertight model with finite-sized struts. The newly formed triangles are connected to form the inner surfaces of six prism-shaped solid struts, with the original triangular tetrahedron faces forming the outer surfaces. In this way, struts are grown from the faces inwards, such that the outer shape is preserved. These steps are repeated for all individual elements, resulting in a porous interconnected strut-architecture.

Related Links:
Queensland University of Technology
Singapore Polytechnic